#background_1{
    background-image: url("../drawable/desktop.jpg");
    height: 1200px;
    background-position: center 0;
    background-repeat: no-repeat;
    background-attachment: fixed;
    background-size: cover;
    -webkit-background-size: cover;
    -o-background-size: cover;
    -moz-background-size: cover;
    -ms-background-size: cover;
}
.text-with-hr {
    text-align: center;
    position: relative;
    z-index: 2;
}
/*
横线，并通过z-index：-1将or附近的横线遮盖住
*/
    .text-with-hr:before {
    position: absolute;
    content: '';
    top: 20px;
    left: 0px;
    width: 100%;
    border-bottom: 3px dashed gray;
    z-index: -1;
}
.text-with-hr span {
    display: inline-block;
    background: white;
    padding: 10px;
}
